This invention relates to the apparatus and a method for installing a new bull gear on the trunnion shaft of a BOF or basic oxygen furnace. The steelmaking vessel in a BOF is supported by a gimbal like suspension system which tranmits loads to a pair of trunnion shafts journaled within bearings mounted on the structural foundation. A large diameter bull gear is attached to one end of the trunnion shaft on the drive side of the BOF, and a drive means, which includes a plurality of motors, pinions and brakes, drives the bull gear to rotate the steelmaking vessel about a horizontal axis.
Occasionally, throughout the long service life of a BOF, it may become necessary to replace a worn bull gear. In the past, such refittings have been very labor intensive as the workers struggle to handle the immense furnace parts and use their own innovative skills to apply force and leverage to install the new gear.
One past procedure, which is still used to install a new bull gear onto a trunnion shaft, comprises drilling, taping and threading, into the end face of the drive side trunnion shaft, long studs which extend in a direction away from the shaft face. The long studs are arranged to correspond with apertures extending through a plate which is bolted to one face of the new bull gear. An overhead crane is used to align the new bull gear with the trunnion shaft and the apertures of the plate are carefully adjoined with the threaded studs. Spacers and nuts are then threaded onto the studs and impact wrenches are used to slowly tighten the nuts and force the new ball gear onto the shaft. The described refitting procedure of the past has been known to take as long as up to 24 hours to complete the installation of a new bull gear.